Earth's ozone layer steadily recovering over time
For the first time, researchers have found direct evidence that efforts to repair the ozone layer are working.

Joseph Scalise | Apr 19, 2018

Earth's ozone layer over Antarctica appears to be healing itself, according to a new studypublished in the journal Geophysical Research Letters.

The ozone is an important part of the atmosphere that protects Earth's surface from harmful rays. Researchers first found evidence the layer had a large hole in it during the mid-1980's. At that time, they alsodetermined the tear was the result of human-produced chemicals known as chlorofluorocarbons (CFCs).

Though past studies have shown that the gash can shrink or increase from year to year, the new study is the first time scientists have directly measured shifts in chlorine levels -- the main element behind ozone depletion -- above Antarctica.

In the research, a group of scientists from NASA's Goddard Space Flight Center looked directly at ozone-destroying chemicals in the atmosphere.To do that, they used the Microwave Limb Sounder (MLS) aboard the Aura satellite to collect ozone data from between 2005 and 2016. While the device is not able to detect chlorine atoms, it can pick up hydrochloric acid, which forms when chlorine atoms react with methane and bond with hydrogen.

CFC's typically break down during warmer months, a process that causes them to produce harmful chlorine. However, during the winter that chlorine binds with methane once the ozone is destroyed. As a result, the team looked at the layer daily throughout that time.

"During this period, Antarctic temperatures are always very low, so the rate of ozone destruction depends mostly on how much chlorine there is," said lead author Susan Strahan, an atmospheric scientist from NASA's Goddard Space Flight Center, in a statement. "This is when we want to measure ozone loss."

After collecting their data, the researchers found that there was a 20-percent decrease in ozone depletion between 2005 and 2016. That is a significant recovery rate that shows the ozone is slowly making a comeback as time goes on. Though the hole itself is not directly getting smaller, the recovery is a step in the right direction and shows that efforts to protect the ozone are working.

"This gives us confidence that the decrease in ozone depletion through mid-September shown by MLS data is due to declining levels of chlorine coming from CFCs," added Strahan, according to "But we're not yet seeing a clear decrease in the size of the ozone hole because that's controlled mainly by temperature after mid-September, which varies a lot from year to year."

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